Nano and Micro Indicators Driving Circular Economy Decisions
The shift from a linear economic model to a circular economy has gained momentum across academia, governance, and industry. A circular economy seeks to decouple economic growth from finite resource consumption, eliminate pollution, and maximize the value extracted from energy and materials. As this paradigm becomes embedded in corporate and governmental strategies, organizations face the challenge of measuring their progress toward circularity with credible, coherent indicators.
The maxim “what gets measured, gets done,” as cited by Nuñez-Cacho et al. (2018), underscores the necessity for consistent measurement tools. Circular metrics are increasingly used to communicate with stakeholders ranging from customers to regulators. The World Business Council for Sustainable Development (2018) stresses that transparent reporting of circular initiatives is vital for attracting investment and public trust. However, without precise definitions and scope, assessments risk becoming superficial.
Kirchherr et al. (2017) define a circular economy as “an economic system that replaces the ‘end of life’ concept with reducing, alternatively reusing, recycling, and recovering materials in production/distribution and consumption processes,” operating at micro, meso, and macro levels. This study extends that framework by introducing a nano level, focusing on products, components, and materials throughout their lifecycle. Saidani et al. (2017) describe this as “the circularity of products, components, and materials, included in three wider systemic levels, all along the value chain and throughout their entire lifecycle.”
Indicators, as explained by Saidani et al. (2019), are analytical tools designed to simplify complex information, enabling tracking, monitoring, and performance measurement. In the context of circularity, they assess the alignment of material or energy flows, products, processes, or systems with circular economy strategies such as redesign, disassembly, recycling, and renewable energy use. Higher circularity reflects closer adherence to these guiding standards.
The macro level encompasses city, regional, or national initiatives, involving infrastructure redesign in areas like clean energy and transportation. The meso level applies to industrial eco-parks and inter-enterprise collaborations, often referred to as industrial symbiosis. The micro level addresses circularity at the scale of consumers, individual companies, or products. Yet, the broad scope of the micro level can lead to ambiguity. Metrics labeled as micro-level indicators may fail to capture the nuanced impacts of specific product designs or components.
Introducing the nano level addresses this gap by isolating product-specific circularity from overall corporate performance. This distinction enables decision-makers to target strategies more precisely within production processes, benefiting higher levels of circularity. Huamao and Fengqi (2007) emphasize that these levels are interdependent; improvements at the nano level can propagate upward, influencing meso and macro outcomes.
The research presented builds on prior reviews by Kristensen and Mosgaard (2020), Lindgreen et al. (2020), Parchomenko et al. (2019), and Saidani et al. (2019), but uniquely separates nano- and micro-level indicators. It also maps each indicator to the three pillars of sustainability—environmental, economic, and social—and to life cycle stages: take, make, use, and recover. This approach supports decision-makers in selecting indicators that align with specific sustainability objectives and lifecycle phases.
The methodology follows PRISMA guidelines (Moher et al., 2009) for systematic literature review, focusing on peer-reviewed sources. The resulting portfolio of indicators underwent bibliometric analysis and detailed examination to answer three core questions: why divide circular economy levels into nano and micro; whether the three sustainability pillars can be assessed through circularity indicators; and which life cycle stages are covered by the analyzed indicators.
Findings reveal that without the nano level, assessments at the micro scale risk oversimplification, obscuring the role of individual product design choices. Furthermore, many indicators do address multiple sustainability pillars, though coverage varies. Life cycle stage mapping shows that while some indicators span all stages, others focus narrowly, underscoring the importance of aligning indicator selection with intended scope.
By refining the granularity of circularity assessment, this work equips engineers, designers, and sustainability strategists with tools to better understand and improve the circular performance of products and processes. The clear separation of nano and micro levels offers a pathway to more targeted interventions, ensuring that measurement drives meaningful progress toward the environmental quality, economic prosperity, and social equity envisioned by the circular economy.
